In the fiber optics field, the need frequently arises to connect or disconnect connectors and adapters arise in both single channel or multiple channel connectors and adapters. The invention here disclosed applies primarily to single fiber applications. There is a continuously increasing demand for higher density interconnect systems in fiber optics applications, especially in those cases where multiple fiber connectors or multiple fiber ferrules are not conveniently reachable due to small size, routing or other considerations.
Generally, modern single fiber optical connector plugs are manufactured with ferrule diameters ranging from 1.25 to 2.5 millimeters. The introduction of sub-millimeter diameter ferrules has resulted in miniature single fiber optical connectors and adapters that allow very high density configurations. In the fiber optics field the need frequently arises to transfer light from one fiber to another either permanently or temporarily. Optical connector plugs are one of the solutions used for this purpose. Fibers terminated with optical connector plugs can be coupled together and disconnected when necessary, either to end the connection or to route the light to a different fiber. Optical connector plugs can be of the single or multiple fiber variety. Single fiber connector plugs (simplex connector plugs) provide the connection of only one fiber to another single fiber. In multiple fiber connector plugs several fibers are simultaneously coupled with another set of similar fibers. The invention here disclosed applies primarily to single fiber applications.
Traditionally, in simplex connector plugs the connection is achieved by the use of cylindrical ferrules. The ferrules, which can be manufactured from several materials, including ceramics, metal, plastic and glass, have in their center a coaxial channel of a diameter slightly larger than the optical fiber. The optical fiber is inserted in the channel and maintained fixed by the use of adhesives, such as epoxy, or mechanical clamping. One end of the fiber is made to be flat or protrude slightly from the end surface of the ferrule and is then terminated, generally by a polishing procedure or other means that provide a very smooth surface.
Two connectors (otherwise referred to as “connector plugs”) are mated with the help of an adapter. The connector plugs comprise the ferrule and the ferrule holder. The adapter has in most cases an internal cylindrical sleeve that aligns the ferrules of both connector plugs. Modern fiber optic connectors usually have a spring mechanism that pushes the ferrules towards one another with a controlled force, in order to achieve physical contact of both fiber ends, thereby improving the optical performance of the connection.
The termination or polishing of the fiber ends is a very involved and delicate procedure which results in the fiber position being either slightly below or above the ferrule end-face surface. The protrusion of the fiber from the ferrule end has to be controlled to very tight tolerances in order to avoid damage of the fiber ends when in physical contact. The pressure between fibers has to be kept in a narrow range in order to keep the glass in its elastic region and thereby prevent fiber rupture as well as preventing the movement of the fibers inside the ferrule channels (pistoning) when the two connector plugs are mated. It is also very important to obtain a very smooth surface free of scratches and other defects, especially in the central core section of the fiber where the light travels. In particular, since ferrule ends and fibers are generally polished together, it is necessary to prevent released ferrule material from damaging the fiber ends during this procedure. The introduction of very small ferrule diameters makes it easier and faster to polish the fiber during the polishing procedure.
Keeping fiber optic connector plugs free from contaminants such as dirt or dust is also very important. Dirt or dust on fiber ends can scatter or absorb light, causing excessive loss of signal and corresponding poor system performance. Presence of contaminants inside the connector plug could cause misalignment with similar consequences. Likewise, because of the intensity of the light being transferred, it is important to shelter users from unintended viewing so as to prevent eye injury.
There is also a continuously increasing demand for higher density interconnect systems in fiber optics applications, especially in those cases where multiple fiber connector plugs or multiple fiber ferrules are not convenient due to routing or other considerations. Generally, modern single fiber optical connector plugs are manufactured with ferrule diameters ranging from 1.25 to 2.5 millimeters. The introduction by the present invention of sub-millimeter diameter ferrules has resulted in a very small single fiber optical connector plug that allows very high density configurations.